This invention relates to a device for automatically stopping and restarting an engine.
Tokkai Hei 8-61110 published by the Japanese Patent Office in 1996 discloses an engine automatic stop/restart device which does not perform an engine automatic stop control on a rising hill so that the vehicle does not move backwards.
However, in this type of engine automatic stop/restart device, when the vehicle is running a location where there are many ascending and descending slopes, there are few opportunities for automatically stopping the engine, so fuel consumption and exhaust gas cannot be suppressed. On the other hand, it may be possible to supply an exciting current constantly to a motor in order to restart the engine promptly whenever an automatic stop of the engine is performed. However, constant supply of the exciting current makes power consumption increase and fuel cost-performance deteriorate.
It is therefore an object of this invention to promptly restart an engine only when a vehicle has to start rapidly, such as when the vehicle has temporarily stopped on a rising hill, and thus to minimize loss of fuel cost-performance.
In order to achieve above object, this invention provides an engine automatic stop/restart device of a vehicle, the vehicle having a drive wheel, and a transmission mechanism which transmits a creep force to the drive wheel according to the rotation of an engine.
The automatic stop/restart device comprises a motor for starting the engine, an inverter for supplying an exciting current and a torque current to the motor, a sensor which detects that the vehicle is stationary, a sensor which detects that a brake pedal is depressed, a sensor which detects that an accelerator pedal is depressed, and a microprocessor.
The microprocessor programmed to stop the engine automatically when the vehicle is stationary with the brake pedal depressed, determine whether or not an excitation of the motor is required before startup of the motor, supply the exciting current to the motor before startup of the motor when the excitation of the motor is required before startup of the motor, inhibit supplying the exciting current to the motor before startup of the motor when the excitation of the motor is not required before startup of the motor, and restart the engine by supplying the torque current in addition to the exciting current to the motor for startup of the motor, when the accelerator pedal is depressed after the engine has automatically stopped.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.